gistfile1.c

$ cat foo.c                                                                                       
#include <stdio.h>

void repeat(int n, void (^block)(int)) {
    for (int i = 0; i < n; ++i) {
        block(i);
    }
};

int main() {
    int x = 42;

    repeat(10, ^(int n) {
        printf("%d\n", x + n);
    });

    return 0;
}
$ clang foo.c && ./a.out                                                                          
42
43
44
45
46
47
48
49
50
51